Exhaust muffler including plural venturi elements



H. A. DORMAN 2,502,709

EXHAUST MUFFLER INCLUDING PLURAL VENTURI ELEMENTS A ril 4, 1950 5 Sheets-Sheet 1 Filed Nov. 1, 1940 BY W WQJW

H. A. DORMAN April 4, 1950 EXHAUST MUFFLER INCLUDING PLURAL VENTURI ELEMENTS Q 3 Sheets-Sheet 2 Filed Nov. 1, 1940 P 1950 H. A. DQRMAN EXHAUST MUFFLER INCLUDING PLURAL VENTURI ELEMENTS 3 Sheets-Sheet 3 Filed Nov. 1, 1940 INVENTOR.

Patented Apr. 4, 1950 UNITED STATES OFFICE EXHAUST MUFFLER INCLUDING 'PLURAL VENTURI ELEMENTS.

Harley A. Dorman, Detroit, Mich.

ApplicatioirNovember 1, 1940, Serial N 363,861

. 11.0laims. 1

The object of my invention is torprovide-a special mufflerfor deadening the sound from an internal combustion engine exhaust, and at the same time greatly reduce the engine back pres.- sure to a minimum.

Another object is to constructa mufiler' that is simple in construction, easily and efliciently installed on any engineunit and that can be manufactured at avery low cost.

These objects are secured in thepreferred form by the construction and arrangement of parts more fully hereinafter set forth.

Similar parts on all. drawings are marked: by similar numerals or letters.

Fig. l is a longitudinal sectional view through the assembled muffler, along the centerline. there on, showing its generalconstruction and arrangementof the various units mounted therein.

Fig. 2 is an end view of the assembled. mufiler showing the tubular intake port for connecting with the engine exhaust.

Fig. 3 is the opposite end view of the muffler, showing the-restricted exhaust port walls leading therefrom.

Fig. 4 is a cross-sectional view taken on the line: 4-4 of the Fig. 1, showing the formation and the relative position of one-setv of muffler units as used therein.

Fig. 5 is also a cross-sectional view taken on theline 5-5 of the Fig. 1, showing the formation and. position of the alternate set. of units'utilizedv therein.

Fig. 6 is a modified cross-sectional view taken on the line 4-4 of the Fig. 1, showing aslight distortion of the inner-unitsto facilitate'manufacturing and assembly requirements, over that shown in the Fig. 4.

Fig. 7 is also a modified cross-sectional view as taken on the line 5-5 of the Fig. 1, illustrating a similar distortion of the corresponding inner units over those shown in the Fig. 5.

Fig. 8 is a vertical'sectional view through one ofthe Venturi tubes illustrating a slight modification of the-expanding or defusing chamber.

Fig. 9 is also a vertical sectional viewthrough' amodified Venturi tube for a more controlledde fusion of the passing gases.

Fig. 10 is a longitudinal sectional view as taken along the mufiler centerline and similar to that shown in the Fig. l, but with the external air dome and chamber omitted.

Fig. 11 is a similar longitudinal sectional view. but further modified by the omission of thecentral nozzle section also.

In accomplishing my object I have applied the combination of several well known principlesaffecting sound waves, especially for gases con-.- trolled byVenturi and ejector tubes, and at the same time utilized the kinetic energy and expansion of gases for'lowering the backpressure within the connected unit.

It is a-well' known principle that sound waves will'not pass through a vacuum, and are likewise affected or diminished as a vacuumcondi-tion is approached, and further sound waves travel in straight lines. It is therefore logical that if the carrying medium, gas. in this case, can be subjected to varying. densities by successive contractions and expansions, thesound waves themselves may likewise be affected and diminishedor possibly destroyed by successive low pressure areas created therein, and further affected by the diffusion of lines of travel through the intermingling gases.

I will now describe more fully the detailed construction of my device referring to the drawings and the marks thereon, illustrating my invention by the preferred'form of construction shown in Figstl to f the drawings.

The casing l ismade of suitable sheet metal, cylindrical in design, and is provided with head members 2 and 3secure1ymounted therein at oppositeends-of the casing. The head section 2 is provided with a tubular intake port a designed forreceiving the end of the engine exhaust pipe thereon. The head section 3 is preferably formed with a flattened aperture 1) providing an exhaust outlet port for the unit, although it may be made cylindrical, orother shapes, if desired. Both heads 2 and 3 are securely attached to the casing preferably by the'rivets 4. or other suitable means such aswelding, etc. Within the casing I, adjacent the in let'head' 2, is mounted aflanged cylindricalairdome 5 of some pre-determined length, and preferably sealed with the casing wall by the fitted flange 0, but open at the opposite end thereof nearestthe-intake port, forming an outer compression chamber 01. The air-dome 5 is retained in position separated from the casing head 2; by the attached spacers 6 engaging the head walls; Within the open end of the cylindrical air-dome- 5, adjacent the exhaustinlet port a, is mounted the enlarged. end of a Venturi tube 1, fittedand attached thereto preferably by rivets 8; or by a welding process. The Venturi tube 1 is formed of two conical surfaces e and f, of uneven lengths, joined at their smaller ends by a. short cylindricalthroatsection g. The cone section e acts .somewhat as-i a compression chamber, while.

the shorter outlet section. acts aSua diffuser asoavoc T 'f for the gases, and the intervening throat g creates the low pressure area. Within the mouth of the Venturi tube 1, above the throat section g, is mounted a smaller conical nozzle section 9, positioned concentric with the Venturi tube section e and separated therefrom by the interposed separators l0, providing a clear passage therebetween, and as illustrated in the Figs. 1 and 4 of the drawings. However, if desired to cheapen construction costs, the nozzle 9 may be somewhat distorted as illustrated in Fig. 6. It is preferred that the nozzle 9 also be made of the Venturi construction, although a straight conical nozzle section will produce very good results. The short throat h as herein illustrated, with its flaring outlet wall is suiiiciently separated from the adjoining Venturi section so as not to obstruct the passage space therebetween, and allow the nozzle to react on the ejector principle, producing pulsations between the respective units, modified by the connected air-dome chamber d, as the exhaust gases are forced therethrough, creating the successive high and low pressure sections within the unit A. Adjacent the air dome 5 within the casing l, is mounted a modified air-dome 5a of different sectional length and spacing from its previous unit, and is separated therefrom by attached spacers H extended to engage the flange c. A modified venturi la, similar to I, is fitted and securely mounted within the open end of the air-dome 5a, as in the former case. The venturi 1a is also correspondingly greater in length than the previous venturi l and is provided with a modified throat and defusion sections ga and fa as illustrated in Fig. 5 of the drawings. Likewise, the inner receiving nozzle to is modified in like form and proportions, and is provided with flat outlet throat ha, to aid in the defusion of sound waves. The nozzle 9a is positioned concentric with its inclosing Venturi section 1a and is separated therefrom by spacers ma as in the former case, and this combined section forms the secondary muiiler unit B. The nozzle 9a and venturi la may also be combined by distortion of the inner unit as in the former case, and as illustrated in the Fig. 7 of the drawings. The remaining muffler units are installed alternate A and B sections, and to include any number desired within the chosen length casing I. It is preferable to vary the lengths or the respective unit sections A and B throughout the extended muiiier section, thus producing a greater variation of densities and a slightly more eifective muffier, although it may somewhat increase the manuiacturing cost.

In all cases the throat openings 72. and ha of the nozzles 9 and 9a must be not less than that of the intake port a, and with the respective Venturi openings somewhat larger, in order to secure the lower back pressures within the muffler. These openings may however, be varied to meet the allowable back pressures permitted, depending on the use and application of the mufiier.

With each pulsation from the engine exhaust into the intake port a, the gases are discharged directly into the receiving nozzle 9 utilizing a small portion of kinetic energy of the high velocity gas, causing av slight entrainment of gases outside the nozzle walls, by ejector reaction, thus preventing equalization of pressure throughout the compartment preceding the Venturi tube, and at the same time creating a low pressure area within the nozzle throat h. The flowing gases likewise create a low pressure area on passing through the Venturi throat 9. By adding the air dome chamber at of such length that each will emit sound waves of very low pitch, a space is created which reacts as a cushion to the highly pulsating gas from the engine exhaust, and thereby maintain a more even low pressure within that area. Further, experiments have shown that sound velocities decrease with tube diameters. It would therefore follow that continued successive low pressure areas alternating with high pressure sections, the flow of gases through decreasing tube diameters, and the defusion of sound waves by variations of the Venturi opening s, would ultimately destroy, or greatly diminish their intensity as they pass through the successive mufiier units, and without creating appreciably the back pressure, due to the unrestricted orifices of the nozzle and Venturi tubes. Extensive experiments have fully verified these facts.

It has been found that by alternating the muffler units A and B the best results are attained, and where more variations in the air dome lengths are used, tone beats can be completely eliminated for all engine speeds and without any increase of back pressure.

Fig. 10 illustrates a modification of the preferred form of mufiier, by omitting the air dome .5 and chamber 11. Its operation is similar to the former case except less effective.

Fig. 11 illustrates a further modification of my preferred form of mufiier by a further omission of both the air dome 5 and the receiving nozzle 9, resulting in a still less effective muflier unit, although very serviceable for certain types of engines.

It is apparent my muffler is subject to various modifications without departing from the spirit of my invention, and I not only claim the design herein shown, but any modification thereof that is substantially a substitution of parts or sections herein illustrated.

Having fully described my exhaust muiiler for internal combustion engines, what I claim as my invention and desire to secure by Letters Patent.

1s: 1. An exhaust mufiler for internal combustion engines, comprising an elongated cylindrical 0518-. ingformed with a closing head mounted within opposite ends thereof, an intake port formed through one casing head and an exhaust port provided in the opposite head wall, a series of sound deadening units mounted within said cylindrical casing for the full length thereof, each of said sound deadening units being formed ,of symmetrically positioned Venturi sections of ,diffcrent sizes and lengths arranged so one opens into another, a sound deadening chamber sur rounding said assembled Venturi sections, and each alternate sound deadening unit being formed of different length and with flattened central exhaust aperture walls therethrough po-1 sitioned symmetrically with the casing axis.v

2. An exhaust muffler for internal combustion engines, comprising a cylindrical casing closed atboth ends thereof and provided with an intake and exhaust at opposite ends, a series of sound deadening units mounted consecutively within the cylindrical casing for the full length thereof, each of said sound deadening units comprising an outer compression chamber positioned cone centric with the casing axis, an enlarged Venturi tube mounted within the casing walls and sealed therewith also positioned concentric with the casing axis, a conical nozzle mounted within the in: take end of said Venturi tube, positioned COIL. centric therewith ,and separated therefrom,

means mounted between the nozzle and Venturi tube for retaining same in fixed predetermined positions. and means mounted on said unit for separating same from the next adjacent sound deadening unit.

3. An exhaust mufller for internal combustion engines, comprising an elongated cylindrical casing closed at both ends and provided with intake and exhaust ports at opposite ends thereof, a series of sound deadening units mounted consecutively within the said casing for the full length thereof, each of said sound deadening units comprising an outer circular compression chamber positioned adjacent to the casing walls, a Venturi tube with an enlarged central opening mounted within the casing walls and sealed therewith, positioned concentric with the axis thereof and having its exhaust port projected within the next adjacent sound deadening unit, alternate sound deadening units having their respective Venturi tubes formed at d'ifierent lengths and formed with flattened exhaust aperture walls therein.

4. An exhaust muffler for internal combustion engines, comprising an elongated cylindrical casing closed and both ends and provided with intake and exhaust ports formed at opposite ends thereof, a series of sound deadening units mounted consecutively within said casing for the full lengthv thereof, each of said sound deadening units comprising a flanged cylindrical air-dome ring fitted and mounted within the casing, an enlarged Venturi tube fitted and mounted within the air-dome ring open end, positioned concentric therewith, a conical shaped nozzle mounted within the intake end of the Venturi tube, concentric therewith and separated therefrom by suitable means, and means for separating the different sound deadening units providing intervening spaces therebetween,

5. An exhaust muffler for internal combustion engines, comprising an elongated cylindrical casing having an intake and exhaust end head fitted therein, a series of sound deadening units mounted consecutively within said casing for the full length thereof, each of said sound deadening units comprising a flanged cylindrical air-dome ring fitted within the casing walls and open at one end nearest the muffler intake port, an enlarged Venturi tube fitted and mounted within the open end of the air-dome ring positioned concentric therewith, a Venturi nozzle section mounted within the open end of the Venturi tube concentric therewith and separated therefrom by suitable means, and means for separating the different sound deadening units from each other providing predetermined spaces therebetween, alternate sound deadening units being formed of difierent lengths and provided with flattened exhaust aperture. walls in their respective Venturi tubes.

6. A mufiler for an internal combustion engine exhaust, comprising an elongated cylindrical casing closed at both ends and provided with intake and exhaust ports at opposite casing ends,a series of sound deadening units mounted consecutively within the casing for the full length thereof, each of said sound deadening units comprising a flanged cylindrical air-dome ring fitted and mounted within the casing walls and provided with an open chamber end nearest the muffler I intake port, an enlarged Venturi tube fitted and mounted within the air-dome ring open end positioned concentric with the casing axis, and

means for separating the assembled units providing predetermined intervening spacings therebetween, alternate sound deadening units being formed with flattened exhaust aperture walls on their respective Venturi tubes.

'7. An exhaust mufiler for internal combustion engines, comprising an elongated cylindrical casing closed at both ends and provided with intake and exhaust ports in opposite ends thereof, a series of sound deadening units fitted and mounted consecutively within the casing for the full length thereof, each of said sound deadening units comprising a flanged cylindrical air-dome ring fitted and mounted within the casing walls, said air-dome ring being formed with an open end positioned nearest the muflier intake port, an enlarged Venturi tube fitted and mounted within the said air-dome ring open end, concentric therewith, a diminished Venturi nozzle section mounted within the intake end of said Venturi tube, concentric therewith and separated therefrom by suitable means, and means for separating the different sound deadening units one from another providing predetermined intervening spacings therebetween, alternate sound deadening units being formed of different lengths and provided with flattened exhaust outlet aperture walls on their respective Venturi and nozzle sections.

8. A mufller for exhaust gases comprising an outer casing provided with inlet and discharge openings and a plurality of sets of parallely-arranged Venturi tube elements mounted in spaced relation within said casing for breaking up said exhaust gases into a plurality of streams having difierent speeds of flow.

9. A muiller for exhaust gases comprising an outer casing provided with inlet and discharge openings and a plurality of sets of Venturi tube elements mounted in spaced relation within said casing, said Venturi tube elements of each set having nonapertured continuous walls and arranged in parallel for breaking up the exhaust gases into "a plurality of streams having different speeds oi flow.

10. A muiiler for exhaust gases comprising an outer casing provided with inlet and discharge openings, and a plurality of sets of Venturi tube elements mounted in spaced relation within said casing, said Venturi tube elements of said sets having a difierent cross-sectional area and parallelly arranged for breaking up said exhaust gases into a plurality of streams havin different speeds of flow.

11. A single unit for use in mufflers of exhaust gases comprising an outer Venturi tube element, an arm extending from said outer Venturi tube element, and an inner Venturi tube element formed on said arm.

HARLEY A. DORMAN.

REFERENCES CITED The followingreferences are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,387,614 Reid Aug. 16, 1921 1,800,354 Powell Apr. 14, 1931 1,924,605 Haas et al. Aug. 29, 1933 1,990,837 Morgenstern Feb. 12, 1935 2,023,024 Kittell Dec. 3, 1935 2,075,088 Blanchard Mar. 30, 1937 2,150,768 Hedrick Mar. 14, 1939 

